In the biochemical field, to ensure the continuous metering of blood contents, it is known to use a sample analyzer which comprises three main members. First, there is a rotating plate which bears the blood samples and has at its periphery a plurality of cells intended to receive the blood tubes, said tubes being identified and marked according to the number and kind of analyses that are to be undergone. Beside said first plate, which bears the samples another rotating plate is located which is Finally, a third plate which also rotates is provided at its periphery with transparent cups intended to receive a dosed mixture of blood and reagent. These three plates are advantageously located to define a triangle therebetween so that one or more rotating arms, which each bear a sampling tube, can take a blood sample from a specific cell on the first plate, and then a reagent sample from a flask of the second plate, whereupon said samples are consecutively placed into one of said cups on the rotating plate after the latter has been pivoted up to be located opposite the conveying arm, a washing unit for the sampling tubes being obviously provided between each sampling procedure. When the filling of the cup with said mixture has been completed, the reaction between both components may be carried out and after a certain period of time the mixture can be subjected to a colorimetric analysis This third plate is then moved, by means of a stepwise motor, to locate the cup to be metered opposite a tungsten-halogen lamp which, by means of filters and lenses, projects a suitable light beam onto the cup. The beam horizontally crosses the sample and strikes a metering photosensor which is stationarily mounted at the center area of the reaction plate. The plate is also called a "disposable" plate because after completion of the cup filling and the analysis, the plate is merely taken off the device and replaced by a new plate, the cups of which are ready to undergo a new filling procedure.
This requirement of wholly replacing the disposable plate is a great drawback since the device is non-operable during a substantial period of time which can extend beyond fifteen minutes. This non-operable state is due, on the one hand, to the proper period of time required for replacing the plate, to the zero-point correction thereof and to the restoration of connections, and is also due, on the other hand, to the fact that, after the first cups have been filled again, the first measurement can only be carried out upon completion of the reactions, which are not instantaneously effected. Further, when all the cups are filled, all the reactions must be completed to complete the last analysis. This disadvantage is particularly marked when an urgent analysis is required during the non-operable period of time since it is not then possible to carry the analysis out immediately, before another one, as the device cannot be operated. Further, the plurality of rotating plates requires the use of a number of driving and locating systems and a sampling arm having a long extension to feed the three plates, or several arms each intended for conveying between two adjacent plates. This results in an analyzing device which is bulky and cumbersome.
It has been proposed to replace the reaction plate by a drawer like device, each drawer consisting of a number of cups, the drawers located beside each other or one on top of each other and able to slide with respect to each other by means of translation motion along rectangular position data. ,Thus a set of cups in a drawer could be replaced without interrupting the reactions in operations carried out in the other drawers However, such a system, although attractive, could not readily be applied as the mechanisms which ensure the motions of the various movable members are complicated. Further, these drawer plates are not well adapted to the thermostatic conditions required in the vessels for receiving the mixture